The major objective of this research is to study the development of three aspects of mastery motivation in the first year of life--persistence in problem solving, practicing emerging motor skills and securing feedback from the environment. Mastery motivation is seen as being closely related to cognitive development. The present study will examine the relationships between mastery behavior at 6 and 12 months in a sample of normal children. We shall also investigate the origins of mastery in the early parent-infant relationship. A variety of methods will be used: a series of 12 tasks designed to measure mastery motivation, observations of mother-infant and father-infant interaction in the home, the Bayley Scales of Infant Development. Analyses will focus on continuity in mastery motivation between 6 and 12 months and on the influence of the infant's early experiences with his parents on the development of mastery behaviors.